nobody likes to see a game with a lot of yellows and cautions, but when its needed... and other think mr. Brych ...if the law of football says that kind of foul is cautioned with a yellow you show the yellow... Problably he wants to impress the FIFA that

too much and not enough

control
I don't think he really was in control. He talks, shouts, has often a need to explain. And one time play went on while he was still talking and explaining. Things went on behind his back.

calls
He was very lenient but then suddenly he canceled a goal by Pato because the Milan forward had pushed someone. Something that was allowed until then and something he allowed again. Just not that one time.
Ronaldinho deserved a caution for a bad tackle on Pepe.
And then the Madrid siders had a trick to foul behind Brych's back, situations a referee has assistants for, but not Brych, who chose to ignore their calls if they called. The three of them probably talked about it during the break because the next time it happened Brych drew his card.

neutrality
All players are equal, but some are more bookable that others. You can show a card to Pato (a young punk) for anything, but not Ronaldinho (an ex-God), not even for a bad foul.

style
Too much talking, the leniency (okay sometimes) but then only in certain situations.